Discusses millimeter waves for indoor microcellular communications. The results of propagation experiments conducted at 60.4 GHz (the oxygen absorption band) and 38.25 GHz to determine multipath characteristics in a number of indoor microcell channels employing omnidirectional antennas are presented. Cumulative distribution functions for received signal envelope, as well as corresponding power spectra are given. In addition, a comparison between the fading statistics measured at 60.4 GHz and 38.25 GHz under similar conditions is made. The change in multipath characteristics due to the presence of different building materials is also illustrated. A ray model is developed to represent indoor microcell propagation by considering a direct ray plus rays which have undergone single and double reflections from the walls. Specular floor-reflected and ceiling-reflected rays are included when the antennas radiation pattern does not preclude them. Using this simple model, the signal variations and the amplitude of reflected rays with respect to the line of sight (LOS) ray as functions of mobile receiver position are predicted and used to assist in interpreting experimental results. Theoretical results are found to be in good agreement with measured ones, with the model also being used to predict structure-induced root mean square (rms) delay spread along receiver routes in an indoor microcell environment. This parameter is a measure of multipath conditions in a mobile radio channel and is inversely proportional to the maximum usable data signalling rate of a channel. >

Millimetric wavelengths radiowave propagation for line-of-sight indoor microcellular mobile communications

Measurements were performed in an urban–suburban environment with narrowband and wideband rf probes, which include millimeter–wave frequencies, in order to study propagation characteristics for street level paths. The primary objective of this report is to evaluate the performance of the rf channels in these environments for both line–of–sight and non–line–of–sight paths and to compare a model developed for line-of-sight paths to measurements taken in Denver, CO.

Millimeter–Wave Propagation Characteristics and Channel Performance for Urban–Suburban Environments

Measurements reported are part of a study of propagation characteristics for millimeter–wave communication links operating in an urban#8211;suburban environment. Absorption data were collected for signals propagated through some common building materials at 9.6 (reference frequency), 28.8, and 57.6 GHz. At these same channel frequencies, paths at street level obstructed by office buildings and residential properties were examined in terms of received signal levels resulting from direct penetration and/or propagation by diffraction modes with terminal separation of from 0.1 to 1.2 km. Signal fading was measured for line#8211;of#8211;sight paths up to 0.9 km as the transmitter terminal, operating at 11.4, 28.8, and 30.3 GHz, traveled down an urban street. Narrow#8211; and wide#8211;beam antenna patterns and both modes of linear antenna polarization were used to compare multipath fading characteristics. A unique 30.3 GHz wide bandwidth channel impulse probe was used to record multipath signal amplitudes and delay times, relative to the direct path, for the same antenna parameters indicated above. Impulse response measurements were recorded at about 10 m intervals as the transmitter traveled along the urban street.

Millimeter–Wave Urban and Suburban Propagation Measurements Using Narrow and Wide Bandwidth Channel Probes

Rapid development of personal, portable, radio communications is expected during this decade. A primary example of this is the emergence of personal communication networks (PCN). These networks are similar to today's cellular telephone technology. However, much smaller cell sizes are used and, as a result, the portable phone is much smaller (pocket size) and inexpensive. The use of millimeter waves for PCN services offers many advantages. Models of millimeter–wave propagation on the kinds of paths that will occur in small cells are needed. In this report a geometrical optics model of the propagation of millimeter waves for line–of–sight paths near street level in urban environments is developed. An idealized environment is assumed with flat streets and uniform street widths between flat building walls. The image–space approach is used to index the direct line–of–sight ray and all reflected ray paths between the transmitter and receiver. The model can be used to simulate received signal characteristics for testing system designs. The statistical behavior of signal level can be computed from the model for real world environments for which it is not practical to give a complete description of the complex physical geometry. The model also shows the channel impulse response functions to be expected in urban cells. Calculations from the model are compared with data measured in downtown' Denver at 9.6, 28.8, and 57.6 GHz.

A Model of Millimeter-Wave Propagation for Personal Communication Networks in Urban Settings

Wideband propagation measurements were made in a pecan orchard in Texas during April and August of 1990 to examine the propagation characteristics of millimeter–wave signals through vegetation. Measurements were made on tree obstructed paths with and without leaves.

The study presents narrowband attenuation data at 9.6 and 28.8 GHz as well as wideband impulse response measurements at 30.3 GHz. The wideband probe (Violette et al., 1983), provides amplitude and delay of reflected and scattered signals and bit–error rate. This is accomplished using a 500 MBit/sec pseudo–random code to BPSK modulate a 28.8 GHz carrier. The channel impulse response is then extracted by cross correlating the received pseudo–random sequence with a locally generated replica.

Wideband propagation measurements at 30.3 GHz through a pecan orchard in Texas

: Measurements of millimeter wave propagation in urban areas at 9.6, 28.8 and 57.6 GHz, and a determination of signal levels reflected from several building surfaces, were made to study wave propagation characteristics in a city environment. Principal emphasis was on the evaluation of communications link reliability, detectability and usable bandwidth as a function of position of terminals. Reflected signal level measurements were performed on building surfaces of concrete aggregate, painted smooth concrete with protruding ribs, brick, and metal siding. Multipath measurements were recorded as a function of distance for several runs over paths of about 1 kilometer in the center of the Denver metro area. Non-line-of-sight observations showed a large number of substantial signals arriving from a wide range of angles. This report contains the results and analysis from single-path and multipath and multipath reflections recorded for the study. Included are an evaluation of multipath effects for both urban and non-urban line-of-sight path and measurements of signals received on non-line-of-sight paths, using edge diffraction effects. (Author)

E J Violette

Papers

Urban Millimeter Wave Propagation Studies.